1. Technical Field
The invention relates to a method for identifying characters when entered as strokes. More particularly, the invention relates to a component-based, adaptive stroke order system for fast entry of ideographic language characters.
2. Description of the Prior Art
For many years, portable computers have been getting smaller and smaller. The principal size-limiting component in the effort to produce a smaller portable computer has been the keyboard. If standard typewriter-size keys are used, the portable computer must be at least as large as the keyboard. Miniature keyboards have been used on portable computers, but the miniature keyboard keys have been found to be too small to be easily or quickly manipulated by a user.
Incorporating a full-size keyboard in a portable computer also hinders true portable use of the computer. Most portable computers cannot be operated without placing the computer on a flat work surface to allow the user to type with both hands. A user cannot easily use a portable computer while standing or moving.
Recent advances in two-way paging, cellular telephones, and other portable wireless technologies have led to a demand for small and portable two-way messaging systems, and especially for systems which can both send and receive electronic mail (“e-mail”).
It would therefore be advantageous to develop a keyboard for entry of text into a computer device that is both small and operable with one hand while the user is holding the device with the other hand. Prior development work has considered use of a keyboard that has a reduced number of keys. As suggested by the keypad layout of a touch-tone telephone, many of the reduced keyboards have used a 3-by-4 array of keys.
Chinese, Japanese, and Korean scripts are based on ancient Chinese characters which make up an ideographic language comprising more than 50,000 characters.
The characters of an ideographic language are each composed of simpler, constituent parts known as components. Components are the building blocks of ideographic characters and combine in certain predetermined ways to form the characters of an ideographic language. Under current practice, a set of 214 components is used in various combinations to produce the characters of the Chinese language. Each component, in turn, is made up a series of specific and precisely defined strokes. There are currently about 40 individual stroke shapes in use which, based on variations in size, require the mastery of 82 strokes before practical writing skills for Chinese ideographs are obtained.
Recent work in fonts, following ISO 10646, the Unicode system, has attempted to describe ideographic characters in terms of smaller functional units rather than directly representing all characters as code points in all of their forms and variations. See, for example, Qin Lu, Ideographic Composition Scheme and Its Applications in Chinese Text Processing (date unknown).
The sheer size of ideographic languages presents unique challenges for specifying and identifying individual characters, particularly for data entry and data processing. Various schemes have been proposed and descriptions can be found in the literature. See, for example, Y. Chu, Chinese/Kanji Text and Data Processing, IEEE Computer (January 1985); J. Becker, Typing Chinese, Japanese, and Korean, IEEE Computer (January 1985); R. Matsuda, Processing Information in Japanese, IEEE Computer (January 1985); R. Walters, Design of a Bitmapped Multilingual Workstation, IEEE Computer (February 1990); and J. Huang, The Input and Output of Chinese and Japanese Characters, IEEE Computer (January 1985); R. Odell, System far Encoding a Collection of Ideographic Characters, U.S. Pat. No. 5,109,352 (28 Apr. 1992); R. Thomas, H. Stohr, Symbol Definition Apparatus, U.S. Pat. No. 5,187,480 (16 Feb. 1993); and B. Hu, Y. Hu, Stroke Entry Key Position Distribution and its Screen Prompts, Chinese Patent Application No. 96120693.4 (Published 29 Apr. 1996).
Most of these schemes require that the user enter predefined codes or follow a predetermined order of entry of strokes or components. Strokes for each character must be entered in the traditional order taught in school. But for both native speakers and those who have learned an ideographic language later in life, the order of strokes and components is not always obvious and may be difficult to remember for infrequently used characters. Teachers living in different parts of the countries where the language is written may introduce variations in style and order, and older people have developed their own ordering over the course of decades of writing the characters by hand.
It would be advantageous therefore to provide a scheme for entering strokes and components and selecting characters that would allow or adapt to users' preferred ordering of those strokes or components for each character.